1824.] Mr. Grafs Reply to the Editor. 123 



Article XIII. 



Reply to the Review of Mr. Gray's Elements of Pharmacy. 

 By Mr. S. F. Gray. 



(To the Editor of the Annals of Philosophy.) 



SIR, 18, Burton-street, Burton Crescent, Dec. 23, 1823. 



1 beg leave to thank you for the commendation you have 

 given to my Elements of Pharmacy, in saying that it is calcu- 

 lated to convey a considerable portion of information ; but I 

 must at the same time desire your attention to a few points in 

 the sequel of your review. 



The arrangement is partly taken from Stahl, partly from Biot; 

 and is such as best suited my purpose of training the student to 

 scepticism, or, at least, indifference in theoretical points. 



The definition to which you object is that of Black, with the 

 addition of the last clause, which I was induced to add, because 

 chemists, from the analogy of electricity to galvanism, attempt 

 to explain the phenomena of the former power, although it is not 

 produced by alteration of temperature, or mixture of bodies, but 

 by mere mechanical means, and therefore will not come within 

 the limits of the original definition of Dr. Black. Heat and cold 

 are used in the definition in their popular sense, as two contrary 

 powers, not only because the philosophical ideas of temperature 

 and caloric had not yet been mentioned ; but also because the 

 existence of a frigorific principle having been started, and its 

 partisans not yet extinct, the popular expression, which involves 

 no theory, best suited the cautious character of a sceptic. 



The first error which you say you shall notice occurs in p. 95, 

 and after quoting the passage, you say, " it proves incontestably 

 that Mr. Gray is ignorant of the composition of sulphuric acid, 

 for he has once in words, and three times by symbols, misstated 

 its nature." But I believe you will upon reflection agree with 

 my statement, that sulphuric acid consists of a charge of sulphur 

 united with three of oxygen. I acknowledge that I have cer- 

 tainly erred in respect to oil of vitriol ; but having written ten for 

 one in the first instance, the subsequent repetitions were mere 

 slips of the pen. How easily these occur your own use of the 

 words sulphuric acid for oil of vitriol in this passage shows, 

 and we shall see more proofs hereafter. As it was only intended 

 in this place to explain the mode of using the symbols, the slip 

 is here of no consequence, and indeed it turns out better adapted 

 for that purpose than the truth would have done, as introducing 

 an example of a coefficient sign. In the history of oil of vitriol, 

 p. 138, the composition is stated right. 



In commenting on my exposition of Berzelius's laws of com- 



